What are PrEP and PEP for HIV?

Pre-exposure prophylaxis (PrEP) is a medication taken prior to exposure to prevent an HIV infection, and is highly effective for preventing HIV when taken as prescribed. It reduces the risk of getting HIV from sex by about 99% and from injection drug use by at least 74%.

PrEP is taken by:

• People who have a sexual partner with HIV (particularly if the partner has an unknown or detectable viral load)
• Injectable drug users who have an injection partner with HIV or share drug equipment
• People who have used multiple courses of post-exposure prophylaxis (PEP)

Post-exposure prophylaxis (PEP) is a medication taken to prevent HIV after a possible exposure. PEP should be used only in emergency situations and must be started within 72 hours after a recent possible exposure to HIV. 

PEP is recommended for people who may have been exposed:

• During sex (for example, if the condom broke)
• Through sharing needles, syringes, or other equipment to inject drugs 
• If you’ve been sexually assaulted

PEP is not a substitute for other safe practices (e.g. condom use, avoiding sharing needles) and is not recommended for people who are routinely exposed to HIV (i.e. have an HIV-positive sexual partner).